Option C.) “Life” would complete this sentence.
“You all hate him, and now I see how my wife, children, and maid conspire against his life.”
This sentence implies that because the people hate him, they are planning to eradicate his life. When plugging the other words in, they would not really make sense unless attached to a particular context; however, plugging in the word “life” broadens the situation to imply that the family and maid plan to kill the male.